1. Field of the Invention
The present invention relates to a service quality management device and to a service quality management method that manage a quality of a communication service provided on a network.
2. Description of the Related Art
In a case where an application server provides a predetermined service to other nodes (user terminals etc) on the network, it is general to conduct acceptance control as control for maintaining the quality of the service to be provided. The acceptance control connoted herein is that it is judged based on a predetermined condition whether a request for the service can be accepted or not. For instance, when a SIP (Session Initiation Protocol) server provides a VoIP (Voice over Internet Protocol) service, the quality of service (QoS) is maintained in a way that prevents simultaneous connections for a fixed or greater number of calls as requests for the service by an acceptance control function of the SIP server or the acceptance control function of a product called a session border controller (acceptance control).
This type of conventional acceptance control is to reject the acceptance if there are requests exceeding a present network transfer capacity for the service, but is not a scheme for improving the network transfer capacity for the service request. In other words, the conventional acceptance control results in restricting a number of services provided to users in order to maintaining the quality of service.
On the other hand, as technologies of improving the network transfer capacity, there are a technology (refer to Patent document 1 given below) of improving a throughput by distributing the traffic to a plurality of routes and a technology (refer to Patent document 2 given below) of equalizing loads of respective links in a way that changes routing metric of the respective links by a load sharing server targeting at an IP network. Note that the conventional art related to the present invention of the application is disclosed in the following documents. The conventional art documents are “Japanese Patent Application Laid-Open Publication No. 2001-320420” (Patent document 1), “Japanese Patent Application Laid-Open Publication No. 2001-24699” (Patent document 2), “Japanese Unexamined Patent Publication No. 2005-518716” (Patent document 3) and “Japanese Patent Application Laid-Open Publication No. 2000-286896” (Patent document 4).
In regard to the conventional arts described above, a service provider who wishes to improve profits from providing the services and a degree of satisfaction of the user or a network provider who wishes to effectively utilize the network, has a demand for providing the services to as many users as possible. Further, there is a demand for improving the quality of service with respect to only a certain limited service among the services provided on the network.
The conventional acceptance control technologies having no alternative but to restrict a number of the provided service in order to maintain the quality of service are hard to meet these demands. Moreover, the technology disclosed in Patent document 1 given above targets at a connection-oriented network as by MPLS (Multi-Protocol Label Switching) and therefore has a problem of being unable to be applied to the IP network.
Still further, the technology disclosed in Patent document 2 given below conducts the load sharing control without taking the service into consideration and therefore has a necessity of grasping demand information representing a service request distribution in order to improve the quality in the way of being limited to the specified service. The grasp of the demand information, however, needs observing all the pass-through packets in the routers within the network, resulting in a problem of being hard to actualize in a large-scale network.